llechwedd slate caverns "alice"-related stamps

1) 11 July 1979 – First Alice issue (two versions of this stamp --in English & in Welsh. There are ten stamps in each language on each sheet, with a total of 20 stamps per sheet. Alice and the White Rabbit are drawn in black & the inscriptions are in purple);
2) 22 August 1979 (same as above, but inscriptions in blue);
3) 25 May 1982 – 150th Anniversary of the birth of Lewis Carroll (Tenniel's scene on the train: ticket collector looking at Alice; drawings in black, inscriptions in purple).